Carbon unicorns and fossil futures. Whose emission reduction pathways is the IPCC performing?
Wim Carton – [email protected]
Lund University Centre for Sustainability Studies (LUCSUS)
This is a book chapter in an anthology on the politics of geoengineering. It is published as:
Carton, W. (2020). Carbon unicorns and fossil futures. Whose emission reduction pathways is the IPCC performing? In: Sapinski JP., Buck H., Malm A. (eds) Has it Come to This? The Promises and Perils of Geoengineering on the Brink. Rutgers University Press.
If one is to believe recent IPCC reports, then gone are the days when the world could resolve the climate crisis merely by reducing emissions. Avoiding global warming in excess of 2°C/1.5°C now also involves a rather more interventionist enterprise: to remove vast amounts of carbon dioxide from the atmosphere, amounts that only increase the longer emissions refuse to fall.1 The basic problem with this idea is that the technologies supposed to deliver these “negative emissions” currently do not exist at any meaningful scale. Given the large uncertainties surrounding their feasibility, their expected effects on land use change, food security and biodiversity, and their scalability, it moreover seems improbable that they ever will.2 Indeed, there appears to be something of an unspoken consensus among scientists that the mitigation scenarios represented in the IPCC increasingly mirror science fiction-writing. The European Academies Science Advisory Council for example, in a recent assessment concluded that negative emission technologies (NETs) have “limited realistic potential” to help mitigate climate change on the scale that many scenarios assume will be needed.3 One expert summarized the skepticism well when she recently characterized such technologies as “carbon unicorns”,4 underscoring the widening gap between the level of mitigation that is needed, and the apparent infeasibility of the pathways that are supposed to take us there.
Despite its fantastical nature however, the negative emissions idea has recently burst into the public arena, where it is already leading a life of its own. For skeptics, this raises the concern of a “moral hazard”, or the possibility that the mere promise of future NETs could act as a break on emission reductions in the present.5 Techno-optimist policy makers, the thinking goes, might very well seize on the negative emissions idea as a “get-out-of-jail” card, holding back from rapid near-term decarbonization in the belief that opportunities for future negative emissions offer sufficient guarantee that the climate crisis can be contained. It is above all future generations, and particularly the poorest among them, that would face the consequences when this “high-stakes gamble” eventually backfires and large-scale NETs turn out to be little more than a pipedream.6 At that point, the window of opportunity for avoiding dangerous warming through conventional mitigation would have closed, and the world would be left with the unenviable choice between runaway warming or implementing some of the more dystopian geoengineering technologies that this book documents. These are not empty fears: as I discuss below, the perceived necessity to defer the bulk of mitigation into a discounted future is the exact logic that underpins the rise-to-prominence of NETs in mitigation scenarios.7 How can we expect of policy makers that they guard against wishful thinking when even scientists appear unable to do so? Besides, the negative emissions concept has already strayed beyond the realm of abstract science and policy debates. The business case for mitigation deferral is already under construction, suggesting that NETs are already performing valuable political economic work. This makes it necessary to scrutinize much more closely what is actually going on in the various models that generate the apparent need for negative emissions.
Take the example of Shell. While not exactly known for its vanguard mitigation actions, the company recently released a document in which it outlines its vision to keep global warming to “well below 2°C”.8 Unsurprisingly perhaps, Shell’s “most ambitious climate scenario” turns out to include substantial fossil fuel use well into the future. It for example assumes that demand for oil will grow until about 2025, and then decrease only gradually. By 2050, the year when the world needs to reach net zero emissions in order to stay below 1.5°C,9 oil demand in this scenario would still account for about 85% of current consumption. By 2070, the net zero target for 2°C, fossil fuel production is still responsible for 16.5 GtCO2, or almost half of what it is today. For Shell to be able to claim that these estimates are compatible with the targets of the Paris Agreement, it heavily relies on speculative technologies, in particular carbon capture usage and storage (CCUS) and NETs. It thus assumes that all that remaining fossil fuel carbon can be captured and/or compensated for by storing it in products (6.1 CO2/yr), applying direct CCS to oil and gas installations (3.4 GtCO2/yr), and deploying large-scale bioenergy with carbon capture and storage (BECCS - 6.1 CO2/yr), which is the NET most often favoured in models. In total this would require that “some 10,000 large carbon capture and storage facilities are built, compared to fewer than 50 in operation in 2020”.10 To reach 1.5°C, the company then imagines that an additional effort could be made by planting “another Brazil in terms of rainforest”.11
These astonishing claims fulfill a clear function, even if they are only a scenario exercise, a best-case “possible” future, not a concrete prediction or commitment. The inclusion of NETs and CCUS in Shell’s future scenario constructs a vision in which the risk for stranded assets is minimized. It makes it possible to claim, as Shell does in its Energy Transition Report, that all of the company’s proven and potential fossil fuel reserves could be utilized – around 25 years of reserves at current production rates – while still staying within the limits of the Paris Agreement.12 Invoking a future of large-scale negative emissions in this way suggests that there is no need to cut fossil fuel production before its economic value has been fully recovered, no need for drastic short-term changes in the company’s business model.13 Given the urgency of the climate problem, this surely seems extraordinary. Is Shell making these numbers up? An analysis by Carbon Brief suggests that the math does indeed add up. Despite being somewhat optimistic about future energy demand in general, Shell’s projections of future coal, oil and gas demand, and of the scale at which NETs could be deployed, are all broadly in line with those of 2°C-compatible IPCC scenarios. If anything, Shell’s scenario is at the lower end of how much negative emissions models say could be deployed by the end of the century.14
In itself, of course, it is unremarkable that a fossil fuel company would use all means possible to help justify the continued use of oil and gas, including fostering narratives about the large-scale deployment of future “carbon unicorns”. This, after all, is the company that has known about the dangers of climate change since at least the 1980s and still decided to double down on oil and gas investments.15 More surprising is the fact that this logic appears fully internalized in mainstream climate scenarios, in other words, that IPCC reports appear to feature emission reduction pathways that seem fully compatible with massive continued fossil fuel use in the medium term. More than a “moral hazard”, this suggests some fairly hazardous scientific morals. Surely this should raise a few eyebrows. How is it possible that the world’s most authoritative science on climate change is generative of scenarios that play directly in the hands of the fossil fuel industry? In this chapter I want to explore some of the reasons for why this is occurring. I want to argue that the path that led to the inclusion of negative emissions in models, and from there into the IPCC, was a profoundly ideological one, and that we need to understand it as such to make sense of the way in which negative emissions are already being invoked to justify business-as-usual. Doing so, I suggest, helps us in challenging the now common idea that negative emissions are somehow an inevitable reality of climate politics.
Negative emissions as convenient fiction
To unpack the work that negative emission scenarios perform, we need to start with the science that produces them. The scenarios represented in the IPCC are generated by using so-called integrated assessment models (IAMs), which are designed to model the complex relationship between social and biophysical systems.16 Briefly put, these models seek to project future technological innovation, economic growth, demographic change, energy use, etc., and how these interact with changes in the climate system. A first important observation is that economics plays a central role in this exercise, in that IAMs are generally made to operate in line with mainstream economic theories. The IPCC is quite explicit about what this means. The fifth assessment report (AR5) for example notes that “[t]he models use economics as the basis for decision making. This may be implemented in a variety of ways, but it fundamentally implies that the models tend toward the goal of minimizing aggregate economic costs of achieving mitigation outcomes [...]. In this sense, the scenarios tend towards normative, economics- focused descriptions of the future”.17 The IPCC also acknowledges that models “typically assume fully functioning markets and competitive market behavior” and therefore do not take account of existing asymmetries and (market) power relations.18
This focus on economics is important for a number of reasons. Most directly, it means that climate policy in IAMs is interpreted as the implementation of a carbon price, that is, it is the assumed cost of carbon that gives the main incentive for a specific level of mitigation. Other mechanisms by which transformational change might come about, for example through mass behavioral changes or non- market government interventions on the scale of recent Green New Deal proposals, are largely ignored by the models.19 A second and related constraint lies in the cost-minimization focus that the IPCC mentions. Essentially, IAMs are designed to “maximize overall welfare” and find the most cost- effective emission reduction pathways. This effectively means that they prioritize between different mitigation technologies on the basis of primarily economic and technological criteria, and underplay social, political and broader environmental reasons why society might opt for one mitigation technology over another.20 In fact, this is the main reason why a technology like BECCS can be modelled by IAMs at such obviously unrealistic scales (e.g. requiring a land area twice the size of India). Even when modelers taken into account more explicitly social factors (for example to assess the public acceptability of different technologies), these are usually still translated to economic terms.21
Now, this primary concern in IAMs with optimized, cost-effective mitigation pathways long meant that very few scenarios were compatible with keeping temperatures below 2°C. Up to the fourth assessment report or so, models tended to generate results that stabilized greenhouse gas concentrations at levels that were significantly higher than those corresponding with what are now the Paris Agreement targets.22 As political recognition on the need for a 2°C limit grew, first in Europe and then elsewhere, policy makers asked the modelling community to come up with scenarios that would be consistent with this.23 This confronted modelers with a considerable dilemma. As Parson notes, “[m]ost of the Integrated Assessment Models (IAMs) [...] found that the target could not be met via plausible and cost-effective levels of mitigation”.24 The solution they came up with was as innovative as it is problematic. Modelers decided to include in IAMs novel mitigation options that allow for the removal of CO2 from the atmosphere, primarily BECCS and afforestation. These were not entirely conjured out of thin air, of course. Afforestation had long been promoted as a carbon offsetting strategy, and researchers had put forward the possibility for BECCS already in the late 90s- early 2000s, though it had so far only been considered as a “backstop” option. Now, however, it became the go-to method.25 Not only did this significantly decrease the costs of achieving stringent mitigation targets,26 it also introduced a debt mechanism into the models.27 By allowing for large-scale carbon dioxide removal, it suddenly became possible to exceed carbon budgets in the short-term, on the assumption that this ‘overspending’ would be compensated for by net-negative emissions in the second half of the 21st century.28
The inclusion of NETs in integrated assessment models in this way played a crucial role in upholding the possibility of the 2°C limit. As Dooley et al. argue, “the availability of BECCS proved critical to the cost-efficiency, and indeed the theoretical possibility, of these deep mitigation scenarios, leading to systemic inclusion of BECCS in RCP2.6 scenarios included in AR5”.29 It is worth underscoring what this means. NETs were mainstreamed in IAMs in order to square the request of policy makers (i.e. to provide 2°C pathways) with the specific economic framework within which these models operate. Current scenarios are in this sense the result of a cost-minimization exercise,30 a fully institutionalized effort to keep the costs of mitigation as low as possible. The models are therefore not actually telling us that NETs are a biophysical necessity to achieve stringent mitigation targets. They are merely saying that these technologies are more cost-effective than other forms of mitigation. Whether or not one accepts the need for negative emissions in this sense ultimately depends on whether one agrees with the various economic assumptions upon which the models are based. As I discuss below, there are plenty of reasons not to do so.
The politics of a pathway
Modelers tend to see their work as “objective input[s] to the climate policy debate”,31 as do, presumably, most policy makers. They are generally quite candid about the assumptions that underpin their models but insist that scenarios are still useful, because they are not actually meant to be policy- prescriptive, or offer accurate predictions of the future. Rather, modelers argue, scenarios are merely supposed to be policy-relevant, to “support policy decisions between different choices” and point to those pathways that what would be most efficient.32 The IPCC has in many ways sought to patrol this border between policy-relevant and policy-prescriptive science.33
A rich literature in science and technology studies however suggests that this distinction is difficult to uphold in practice. Scholars in this discipline point out that any kind of scientific knowledge production comes with value-judgements, and therefore inevitably ends up fulfilling some kind of political function.34 The incorporation of NETs in IPCC scenarios is one clear illustration of how, as Turnhout et al. put it, “dominant political discourses compel scientists to create assessments that work within these discourses”,35 a process that involves the articulation of problems that are legible to, and the proposal of solutions compatible with, prevailing political and economic logics. Knowledge production, in other words, is often reflective of existing power relations in society, while at the same time contributing to, and justifying the reproduction of those relations. The future focus and therefore unverifiable and speculative character of scenario production significantly amplifies these dynamics.36 In this, the problem is not that science is political per se, but that its political character remains unrecognized or actively denied by the actors involved, either directly or as a consequence of the methods that are used. As a result, value-laden and contestable assumptions appear as somehow unavoidable or “natural”, which closes opportunities for debate and the involvement of dissenting voices. The use of models, particularly ones as complex as IAMs, further contributes to this process of depoliticization by shrouding assumptions and value judgements behind seemingly technocratic and objective modelling choices.37
Beck and Mahony argue that the increasing importance of modelled emission reduction pathways in the IPCC in this way represents a shift towards a “new politics of anticipation, wherein potentially contestable choices for climate futures are woven into the technical elaboration of alternative pathways”.38 They note that by being included in the authoritative assessments of the IPCC, such pathways do not just describe possible climate futures, but potentially help bring them into being, that is, they perform certain futures as seemingly legitimate, necessary and desirable. IAMs in this sense provide scientific backing for the kind of mitigation scenarios that are “thinkable and therefore actionable”,39 while simultaneously sidelining others. One of the clearest examples of this is the negative emissions idea. Before they appeared in IAMs, negative emission technologies were virtually absent from the climate policy arena. Following their inclusion in models, they appeared in IPCC assessments and from there have become an increasingly common topic in mainstream policy debates. As the above Shell example shows, they have now moved into the delaying tactics of the fossil fuel industry. The modelling community in this way “performed an important legitimating function for the speculative technology of BECCS, pulling it into the political world, making previously unthinkable notions [...] more mainstream and acceptable, as well as perhaps pushing it ahead of policy options (such as radical mitigation) in political calculations”.40 The speculative and contestable inclusion of NETs in influential and seemingly neutral IPCC assessments served to normalize and mainstream the idea that negative emissions are both feasible and necessary.
Taking this one step further, some scholars have argued that the negative emissions idea is performing an important legitimizing role for the existing architecture of climate policy as a whole.41 By perpetuating the idea that cost-effective pathways to 2°C, and now also 1.5°C are still available, the argument goes, the IPCC is providing a rather convenient narrative to governments. The possibility of future NETs appears to suggest that more of the same incremental policies will eventually get us there; that there is no need for drastic or economically “irrational” actions.42 As such it helps preserve a sense of normality against increasingly dire warnings – and observations – of an unfolding climate emergency, against 30 years of political delay in delivering serious mitigation efforts. The science- sanctioned normalization of negative emissions in this sense reproduces the idea that all is as it should be in the magical wonderland of climate politics, where mitigation need not imply efforts to cut actual fossil fuel production, at least not in the short-term. When at the same time this discourse builds on highly improbable projections of the future, on the hypothetical deployment of technologies that – at the scale they are being proposed – reasonably belong in the realm of science fiction; and when it so obviously constitutes a form of risk transfer, in which it is the powers-that-be that stand to gain, while it is future generations that will be left to pick up what pieces remain,43 then the need for critique runs very deep indeed.
Performing the imperative of gradualism
So how did it come to this? To understand how IPCC scenarios end up being “performative” in the way that they are requires that we scrutinize not just model outcomes and the political work that these perform, but also the logics that generate these outcomes in the first place. There is plenty to suggest that the dynamics described in the science and technology literature can in large part be traced back to the various, connected assumptions that underlie IAMs, assumptions that together constitute an ideological commitment to the postulates of mainstream economic theory. This is, of course, hardly a unique case. In important ways it reflects the wider trend by which economics has come to dominate the terms of the climate policy debate – of how to assess and understand both the problem and its potential solutions.
Consider again the focus of IAMs on cost-effective mitigation. Why exactly is it that the prioritization of cost-effective solutions leads to the need for negative emissions? There are a number of intertwined reasons for this, and while I cannot consider all of them here, a few stand out as particularly important. First, it is worth noting that mitigation costs in IAMs are usually calculated on the basis of a comparison with a so-called “baseline”, meaning a counterfactual scenario of what the world would look like in the absence of climate policies. The cost of mitigation in other words is an estimate of what it takes, in economic terms, to move from the assumed baseline to the desired mitigation scenario. Observe that these baselines are necessarily hypothetical exercises, not in the least because, with a few exceptions, models so far do not take into consideration the many feedbacks of a warming climate itself.44 Essentially they assume that economic growth, population growth, consumption, energy demand etc. will continue as an extrapolation of existing trends, despite rapidly increasing temperatures, as if climate change has no societal impact at all. This crucial omission is acknowledged by modelers as a shortcoming, but in itself arguably already invalidates the entire scenario-building exercise. Calculating costs and cost-dependent mitigation pathways in relation to an impossible baseline clearly overstates the benefits of the “no-policy” scenario, and therefore presumably inflates the aggregate costs of mitigation. More generally, it means that the choice of baseline significantly influences the outcomes of the model.45 Modelers generally deal with this by considering a large range of possible baselines, which are grouped together under stylized ‘socioeconomic pathways’.46
To different extents, these baseline scenarios assume continued (and often growing) fossil fuel consumption and trade well into the 21st century.47 Moving to a mitigation scenario then logically implies significantly reducing that consumption and trade as well as its corresponding economic value (since baselines are seen as economically optimal, any deviation from them becomes a cost). The extent to which fossil fuel consumption needs to be reduced, however, and the exact costs this corresponds to, fundamentally depend on the kind of mitigation technologies that are included in the model. For example, if one assumes a future in which no CCS technologies are implemented, then fossil fuel consumption needs to fall rapidly to stay within the targeted temperature limits, reaching zero before the end of the century.48 Indeed, many of the scenarios that explicitly exclude CCS (including BECCS) are unable to generate 2°C-compatible pathways at all, because of prohibitively high costs.49 This not only reflects the substantial investments needed to rapidly replace current high-carbon infrastructure, but also the fact that for many sectors where there are currently few low-carbon technological alternatives on the horizon – think cement and steel production, aviation, etc. – drastic emission cuts would almost by necessity involve cuts in economic production. With CCS, some of those fossil fuels can continue to be used and their corresponding economic value recovered. The inclusion of negative emissions from BECCS in particular extends this effect further. BECCS essentially enlarges the carbon budget while also providing a source of energy, allowing even more fossil fuels to be used in the medium-term.50 Observe here that the cost-effective focus of IAMs in this way renders different mitigation technologies qualitatively substitutable, meaning that as long as a given technology is available and economically attractive (within the assumptions used by the model), it will be prioritized. As noted above, this ignores obvious social justice or environmental sustainability concerns.
From this discussion it appears that the cost of mitigation tends to decrease the more fossil fuels we can continue using. This is obviously not fully true. As the IPCC points out, aggregate mitigation costs in IAMs generally increase when action is delayed.51 The reason for this is fairly simple – scenarios still need to reach 2°C or 1.5°C by the end of the century. The longer mitigation is delayed, the more fossil fuels that are “locked into” a (growing) economy, and the more investments and/or devaluations it will therefore take to eventually bring emissions down to net zero/net negative. The cost of mitigation is therefore not a function of continued fossil fuel use per se, but of the steepness of the mitigation curve, that is, of how quickly fossil fuel consumption needs to fall in order to reach the specified temperature target. The faster fossil fuels are eliminated, the steeper the emission reduction curve, and therefore the higher the cost. This seems like a trivial consideration but it is critical to understand its implications. Since IAMs are designed to minimize mitigation costs, this means that they by definition select for the most gradual reduction in fossil fuel use. As long as emissions and fossil fuel consumption go hand in hand, this also means that they select for the most gradual emission reduction curve. Including CCS in IAMs essentially decouples fossil fuel consumption from emissions, and therefore allows the former to fall more slowly relative to the latter. Negative emissions go even further in that they actually extend the carbon budget and thus stretch out the emission reduction curve itself. The effect is to reduce the rate at which fossil fuel use needs to fall, which in turn leads to lower mitigation costs. One could say that the inclusion of NETs in IAMs in this way serves to recover as much economic value from fossil fuel consumption and trade as possible within the limits of a 2°C or 1.5°C budget.
Some of this “gradualizing” of the mitigation curve is done quite explicitly by modelers themselves. Van Vuuren et al.,52 for example, using an earlier version of the integrated assessment model IMAGE, explain the criteria they used when developing their mitigation pathways as follows:
“[F]irst, a maximum reduction rate was assumed reflecting the technical (and political) inertia that limits emission reductions. Fast reduction rates would require the early replacement of fossil-fuel-based capital stock, and this may involve high costs. Secondly the reduction rates compared to baseline were spread out over time as far as possible – but avoiding rapid early reduction rates and, thirdly, the reduction rates were only allowed to change slowly over time”.53
Kriegler et al.,54 using a different IAM, similarly note that their model does not allow for the early retirement of existing fossil fuel infrastructure. In other words, the models are actively designed so as to avoid the devaluation of economically valuable fossil fuel assets, believing this to be unfeasible, and so as to make full use of the window of opportunity for reaching the desired mitigation target. In this, their assumptions are directly in line with the arguments of the fossil fuel industry. In Shell’s “well- below 2°C” scenario as well, the imperative for NETs logically follows from the assumed inevitability of socio-economic and technological inertia, i.e. the idea that until 2030 or so, “energy system CO2 emissions are largely locked in by existing technologies, capital stock, and societal resistance to change”.55 Modelers and industry interests in this way agree that there is no alternative to incremental change, even if that means conjuring up improbable technological solutions.
These dynamics are reinforced by the idea that future costs and benefits need to be discounted relative to the present. IAMs generally use a discount rate of 5%,56 which means they weigh costs and benefits in the present more heavily than those that will occur in the future. The reasoning here, imported directly from financial markets, is that future generations will be wealthier (given continued economic growth) than current generations, and will therefore better be able to pay for any future costs that arise from climate change. This is a contentious and oft-debated assumption. For one, it assumes, wrongly, that the costs and benefits of mitigation/adaptation, and indeed the impacts of climate change itself, can be straightforwardly captured/compensated for in monetary terms. As above, it also suggests that growth can and will continue despite an accelerating environmental crisis, which seems improbable to say the least. There is furthermore no consensus among economists about what exact discount rate to use, which is unsurprising given the inherently subjective and speculative nature of the exercise.57 As Stanton et al. note, selecting a discount rate essentially means making a judgement about how to value the benefits of avoided warming for future generations, which is “a problem of ethics, not economic theory or scientific fact”.58 A high discount rate is an implicit prioritization of short-term interests over long-term ones, or as Jasanoff pointedly puts it, “erases the distant future as a topic of calculable concern”.59 In the IAMs we are here concerned with, applying a discount rate of 5% has the effect of deferring mitigation costs into the future, when those costs will supposedly be more affordable. Because large-scale NETs are projected to be implemented mainly in the 2nd half of the century, discounting makes them comparatively more attractive than mitigation measures that are rolled out in the near-term, and therefore gives them a direct advantage in the model.
So what is actually going on here? Clearly, the supposed necessity of negative emissions in mitigation scenarios is the result of a number of specific assumptions and value-judgements, all of which can reasonably be questioned. But the problem seems broader than just the negative emissions issue alone. Essentially, what is being performed in IPCC scenarios is the imperative of gradualism, that is, the idea that mitigation needs to be incremental if it is to materialize at all. The “naturalization” of fossil fuel benefits through business-as-usual baselines; the management of the rate of mitigation by way of cost-effective technology choices; the direct “gradualization” of model inputs and the application of a high discount rate; all of these modeling characteristics perform the idea that some degree of emissions are inevitable, indeed, that the economic benefits of fossil fuel production must be defended to the extent possible. Models in this way institutionalize the assumption that short-term devaluation of fossil fuel assets is untenable and economically undesirable, hence that socio-economic inertia is an unavoidable feature of the current energy system. This de facto enacts inertia as some kind of natural law, rather than a condition that is maintained and reproduced through historically- specific socio-economic structures and therefore responsive to political choice.
Connecting integrated assessment modelling to the interests of polluters like Shell, then, is a commitment to the ideology of mainstream economics, a narrow reliance on cost-effectiveness as the most appropriate way to mediate between alternative climate futures. By reducing mitigation to a question of carbon costs and then applying a cost-minimization model to it, IAMs render climate change mitigation legible to vested political and economic interests, but at the same time also delimit the range of mitigation options that seem feasible. As a result, modelled pathways end up being biased against more radical, near-term emission reductions, against opportunities for widespread behavioural changes or the kind of state-driven economic planning proposed by Andreas Malm in this book.60 It then becomes more logical to imagine that warming will be contained by a massive roll-out of fantastical negative emissions technologies than to try and project, for example, a portfolio of more short-term and risk-averse strategies, even if that means accepting a higher economic cost (for some!). By giving IAM-based scenarios center stage in its assessments, the IPCC in this way reproduces the idea that it is the (contestable and flawed) laws of economic theory that should determine the rules of engagement in climate policy, not the laws of the biogeochemical carbon cycle or consideration for the ethical distribution of mitigation risks and responsibilities. The inevitable end-result, ironically, is that the IPCC, as the most authoritative international body on climate change, is providing scientific backing for the kind of delaying tactics that companies like Shell excel in.
The point is to change it
To be sure, there are plenty of good reasons to support certain kinds of carbon dioxide removal, at least in principle. Afforestation is direly needed not just to sequester carbon but also to bend the trend of rapid biodiversity loss. Soil carbon sequestration not only takes carbon out of the atmosphere but also increases soil organic matter and therefore improves soil structure, helps build soil fertility and benefits soil organisms.61 Neither of these however are the silver bullets that IPCC scenarios are projecting with NETs. Implementing these technologies at planetary scale comes with enormous challenges, and it therefore seems problematic to treat them as real alternatives to direct emission cuts. In fact, no new research is needed to demonstrate that afforestation, bioenergy production or CCS are not the convenient and inexpensive mitigation options that they are now being portrayed as. These technologies already exist at smaller scales and have already been extensively studied. The vast literature on carbon forestry, for example, confirms the potential benefits that tree planting offers, but also vividly illustrates the trade-offs commonly involved, including a real possibility for violence and dispossession, project failure, public disapproval, or the marginalization of the interests and voices of those most affected.62 Debates on forest-based carbon offsetting – a mechanism that in many ways overlaps with the logic of negative emissions – furthermore underscore the ethical problems with the idea that land use change should compensate for the continued emissions of fossil fuels. Fairhead et al. in this context speak of the “economy of repair”, or the idea that “unsustainable use ‘here’ can be repaired by sustainable practices ‘there’”,63 where “there” often ends up meaning the developing world, since the “economy of repair” too is a cost-optimizing one. If large-scale negative emissions provide the next frontier for this perverse logic, as seems a real risk, it needs to be challenged and resisted.
I have suggested that a good place to start this task is by scrutinizing the idea that negative emissions are necessary in the first place. It turns out that NETs were introduced in models first and foremost as an economic necessity, given in by the character of the models themselves. Whether or not we accept the inevitability of negative emissions – at scale – is therefore entirely contingent on whether we subscribe to the economic assumptions that they extend from. These assumptions ultimately revolve around the treatment of climate change as primarily a question of cost-minimizing economics. It seems obvious that this is a wholly inadequate way to decide on the most feasible, desirable or appropriate way to cut emissions. It falsely constructs all forms of mitigation as qualitatively equal (ignoring important ethical, political and ecological differences64), perpetuates simplistic assumptions of how change occurs in complex social systems, and orients the mitigation curve towards gradualism despite the social and environmental risks this entails. The cost of mitigation in models is moreover a constructed category, fully dependent on assumed long-term technology costs, the exclusion of climate feedbacks and the choice of discount rates and baselines. Translating this inherently partial approach into concrete mitigation pathways seems like high-risk theoretical myopia and ends up ignoring real opportunities for more just and immediate cuts in greenhouse gas emissions. Modelers might insist that their scenarios are not predictions, but their inclusion into the IPCC still gives them undue real-world validity and political influence. It is illuminating in this respect that Van Vuuren et al. recently published a study that modelled scenarios to 1.5°C with minimal negative emissions, simply by assuming more rapid electrification of the energy system and far-reaching lifestyle changes, among other things.65 While they don’t provide a cost analysis for these scenarios, one can assume that they would be significantly more costly – in the way IAMs assess this – than “standard” mitigation approaches. What this illustrates is that, if one tinkers long enough with inputs and assumptions, it is possible to make these models come up with virtually anything. As Tavoni and Socolow note, this “should make the reader cautious about carrying modeling results into the real world”.66
In the end then, while modelers acknowledge that the choice between different mitigation options remains a political one, their models only give credibility to a select range of options. By reducing climate policy to a question of cost-optimization, IAMs appear to take the cost of mitigation outside of the political debate. They seem to suggest that mitigation needs to be cost-effective if it will materialize at all, which underplays both the scope and the urgency of the change that is needed. The need for rapid, radical emission reductions suggests a need to repoliticize discussions on what forms of mitigation are most appropriate and how we will be paying for it. Surely, if the responsibility of the IPCC extends beyond minimizing the devaluation of fossil fuel assets – as of course it does – then its work should involve highlighting, in a much more direct way, the benefits of certain emission reduction pathways in spite of their cost, that is, to illuminate the many uncertainties and risks of incremental climate policy? Surely assessing opportunities for mitigation should involve not just acquiescing to the inevitability of fossil-infused inertia, but actively challenging it, by providing an open an honest evaluation of the social, economic, political and environmental pros and cons of the full range of mitigation options, including those that are inconvenient to vested political and economic interests?
Of course some economists would fume that no such thing is possible, that high-cost scenarios are politically unrealistic, not policy-relevant; that no politician or business would implement a policy that is not cost-effective. But that would be missing the point entirely. As Alyssa Battistoni rightly observed recently, there are no politically realistic climate change mitigation options.67 There is nothing politically realistic about assuming that large-scale NETs are going to save the day. It merely defers the political inconvenience of implementing those technologies to future generations, pushing the problem out of sight for the current generation of decision makers. To accept this as a matter of fact is to fail to stand up to the magnitude of the challenge, to default on our collective responsibility towards future generations. It is to deny that the only realistic way forward involves a fundamental change of politics. Moreover, even if it were true that political decisions are necessarily made in narrowly defined, cost-optimizing ways, hence that the political arena is locked into long-term socio- economic inertia – why should scientists have to play by that game? Why would modelers need to build political feasibility into their models, if all this does is lead to future scenarios populated by carbon unicorns? Why should the academic community not point out that there is in fact a choice here, even if it is an unpopular and economically difficult one? When climate policies turn out to be so woefully inadequate, it is perhaps time for the scientific community to become a little less policy- relevant, and a little more confrontational in its engagement with decision makers.68 It is perhaps time to start refusing to perform, through seemingly innocuous models, the kind of gradualism that has long-ago proven incapable of taking us out of this mess.
1 Schleussner et al., “Science and Policy Characteristics of the Paris Agreement Temperature Goal”; Peters and Geden, “Catalysing a Political Shift from Low to Negative Carbon”; Intergovernmental Panel on Climate Change (IPCC), “Global Warming of 1.5°C: An IPCC Special Report on the Impacts of Global Warming of 1.5 °C above Pre- Industrial Levels and Related Global Greenhouse Gas Emission Pathways, in the Context of Strengthening the Global Response to the Threat of Climate Change”; Intergovernmental Panel on Climate Change (IPCC), Climate Change 2014: Mitigation of Climate Change.
2 see Anderson and Peters, “The Trouble with Negative Emissions”; Scott and Geden, “The Challenge of Carbon Dioxide Removal for EU Policy-Making”; Smith et al., “Biophysical and Economic Limits to Negative CO2 Emissions”; Larkin et al., “What If Negative Emission Technologies Fail at Scale? Implications of the Paris Agreement for Big Emitting Nations”; Fuss et al., “Betting on Negative Emissions”; Harper et al., “Land-Use Emissions Play a Critical Role in Land-Based Mitigation for Paris Climate Targets.”
3 European Academies Science Advisory Council (EASAC), Negative Emission Technologies: What Role in Meeting Paris Agreement Targets?
4 McGrath, “Caution Urged over Use of ‘carbon Unicorns’ to Limit Warming.”
5 Markusson, McLaren, and Tyfield, “Towards a Cultural Political Economy of Mitigation Deterrence by Negative Emissions Technologies (NETs)”; Lenzi, “The Ethics of Negative Emissions”; Minx et al., “Negative Emissions: Part 1 - Research Landscape, Ethics and Synthesis.”
6 Shue, “Climate Dreaming: Negative Emissions, Risk Transfer, and Irreversibility”; Anderson and Peters, “The Trouble with Negative Emissions.”
7 Minx et al., “Negative Emissions: Part 1 - Research Landscape, Ethics and Synthesis.”
8 Shell, “Shell Scenarios: Sky - Meeting the Goals of the Paris Agreement.”
9 Intergovernmental Panel on Climate Change (IPCC), “Global Warming of 1.5°C: An IPCC Special Report on the Impacts of Global Warming of 1.5 °C above Pre-Industrial Levels and Related Global Greenhouse Gas Emission Pathways, in the Context of Strengthening the Global Response to the Threat of Climate Change.”
10 Shell, “Shell Scenarios: Sky - Meeting the Goals of the Paris Agreement,” 6.
11 Vaughan, “Shell Boss Says Mass Reforestation Needed to Limit Temperature Rises to 1.5C.”
12 Shell, “Energy Transition Report.”
13 Carton, “‘Fixing’ Climate Change by Mortgaging the Future: Negative Emissions, Spatiotemporal Fixes, and the Political Economy of Delay.”
14 Evans, “In-Depth: Is Shell’s New Climate Scenario as ‘Radical’ as It Says?”
15 Carrington and Mommers, “‘Shell Knew’: Oil Giant’s 1991 Film Warned of Climate Change Danger.”
16 Note that there is also a different set of IAMs, which are used to calculate the social cost of carbon and are not used in producing emission reduction pathways. These more simple models make a cost-benefit analysis of different emission reduction pathways, by weighing the economic costs of various mitigation options against the risks (again, in economic terms) of climate change. This is the kind of thinking that for example leads William Nordhaus – using his DICE model – to the conclusion that the economically “optimal” level of warming is somewhere from 2.6°C to 3.5°C and that “the advantage of geoengineering over other policies is enormous”. See Nordhaus, “Projections and Uncertainties about Climate Change in an Era of Minimal Climate Policies”; Nordhaus, A Question of Balance: Weighing the Options on Global Warming Policies; Stern, “The Structure of Economic Modeling of the Potential Impacts of Climate Change: Grafting Gross Underestimation of Risk onto Already Narrow Science Models.”, Nordhaus, “An Optimal Transision Path for Controlling Greenhouse Gases,” 1319.
17 Intergovernmental Panel on Climate Change (IPCC), Climate Change 2014: Mitigation of Climate Change, 422. 18 Intergovernmental Panel on Climate Change (IPCC), 422.
19 Beck and Mahony, “The Politics of Anticipation: The IPCC and the Negative Emissions Technologies Experience.”
20 Larkin et al., “What If Negative Emission Technologies Fail at Scale? Implications of the Paris Agreement for Big Emitting Nations”; Van Vuuren et al., “Open Discussion of Negative Emissions Is Urgently Needed.”
21 Carbon Brief, “Q&A: How ‘Integrated Assessment Models’ Are Used to Study Climate Change.”
22 Tavoni and Socolow, “Modeling Meets Science and Technology: An Introduction to a Special Issue on Negative Emissions”; Van Vuuren et al., “Stabilizing Greenhouse Gas Concentrations at Low Levels: An Assessment of Reduction Strategies and Costs.”
23 Tavoni and Socolow, “Modeling Meets Science and Technology: An Introduction to a Special Issue on Negative Emissions”; Beck and Mahony, “The IPCC and the Politics of Anticipation.”
24 Parson, “Climate Policymakers and Assessments Must Get Serious about Climate Engineering,” 9228.
25 Hickman, “Timeline: How BECCS Became Climate Change’s ‘Saviour’ Technology.”
26 Van Vuuren et al., “Stabilizing Greenhouse Gas Concentrations at Low Levels: An Assessment of Reduction Strategies and Costs”; Azar et al., “Carbon Capture and Storage from Fossil Fuels and Biomass - Costs and Potential Role in Stabilizing the Atmosphere.”
27 Carton, “‘Fixing’ Climate Change by Mortgaging the Future: Negative Emissions, Spatiotemporal Fixes, and the Political Economy of Delay.”
28 Geden, “The Paris Agreement and the Inherent Inconsistency of Climate Policymaking”; Geden, “Politically Informed Advice for Climate Action.”
29 Dooley, Christoff, and Nicholas, “Co-Producing Climate Policy and Negative Emissions: Trade-Offs for Sustainable Land-Use,” 6.
30 Parson, “Climate Policymakers and Assessments Must Get Serious about Climate Engineering.”
31 Dooley, Christoff, and Nicholas, “Co-Producing Climate Policy and Negative Emissions: Trade-Offs for Sustainable Land-Use,” 7.
32 Carbon Brief, “Q&A: How ‘Integrated Assessment Models’ Are Used to Study Climate Change.”
33 Beck and Mahony, “The Politics of Anticipation: The IPCC and the Negative Emissions Technologies Experience”; Dooley, Christoff, and Nicholas, “Co-Producing Climate Policy and Negative Emissions: Trade-Offs for Sustainable Land-Use.”
34 Turnhout, “The Politics of Environmental Knowledge”; Jasanoff, States of Knowledge: The Co-Production of Science and the Social Order.
35 Turnhout, Neves, and De Lijster, “‘Measurementality’ in Biodiversity Governance: Knowledge, Transparency, and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (Ipbes),” 583.
36 Low, “The Futures of Climate Engineering.”
37 Demeritt, “The Construction of Global Warming and the Politics of Science”; Mahony and Hulme, “Epistemic Geographies of Climate Change”; Beck and Mahony, “The Politics of Anticipation: The IPCC and the Negative Emissions Technologies Experience.”
38 Beck and Mahony, “The IPCC and the Politics of Anticipation,” 312.
39 Beck and Mahony, “The Politics of Anticipation: The IPCC and the Negative Emissions Technologies Experience,” 5.
40 Beck and Mahony, 4.
41 Geden, “The Paris Agreement and the Inherent Inconsistency of Climate Policymaking.”
42 Larkin et al., “What If Negative Emission Technologies Fail at Scale? Implications of the Paris Agreement for Big Emitting Nations.”
43 Shue, “Climate Dreaming: Negative Emissions, Risk Transfer, and Irreversibility.”
44 Carbon Brief, “Q&A: How ‘Integrated Assessment Models’ Are Used to Study Climate Change”; Intergovernmental Panel on Climate Change (IPCC), Climate Change 2014: Mitigation of Climate Change, chap. 6.
45 cf. Van Vuuren et al., “Stabilizing Greenhouse Gas Concentrations at Low Levels: An Assessment of Reduction Strategies and Costs”; Riahi et al., “The Shared Socioeconomic Pathways and Their Energy, Land Use, and Greenhouse Gas Emissions Implications: An Overview.”
46 Riahi et al., “The Shared Socioeconomic Pathways and Their Energy, Land Use, and Greenhouse Gas Emissions Implications: An Overview.”
47 Intergovernmental Panel on Climate Change (IPCC), Climate Change 2014: Mitigation of Climate Change, sec. 18.104.22.168.
48 Klein et al., “Global Economic Consequences of Deploying Bioenergy with Carbon Capture and Storage (BECCS).”
49 Intergovernmental Panel on Climate Change (IPCC), Climate Change 2014: Mitigation of Climate Change, chap. 6.
50 Kriegler et al., “Is Atmospheric Carbon Dioxide Removal a Game Changer for Climate Change Mitigation?”
51 Intergovernmental Panel on Climate Change (IPCC), Climate Change 2014: Mitigation of Climate Change, sec. 22.214.171.124.
52 Van Vuuren et al., “Stabilizing Greenhouse Gas Concentrations at Low Levels: An Assessment of Reduction Strategies and Costs.”
53 Van Vuuren et al., 131.
54 “Is Atmospheric Carbon Dioxide Removal a Game Changer for Climate Change Mitigation?”
55 Shell, “Sky Scenario,” 23.
56 Intergovernmental Panel on Climate Change (IPCC), Climate Change 2014: Mitigation of Climate Change; Van Vuuren et al., “Open Discussion of Negative Emissions Is Urgently Needed.”
57 Pindyck, “The Use and Misuse of Models for Climate Policy.”
58 Stanton, Ackerman, and Kartha, “Inside the Integrated Assessment Models: Four Issues in Climate Economics,” 174.
59 Jasanoff, “A New Climate for Society,” 242.
60 Larkin et al., “What If Negative Emission Technologies Fail at Scale? Implications of the Paris Agreement for Big Emitting Nations”; see also Beck and Mahony, “The Politics of Anticipation: The IPCC and the Negative Emissions Technologies Experience.”
61 Crews, Carton, and Olsson, “Is the Future of Agriculture Perennial? Imperatives and Opportunities to Reinvent Agriculture by Shifting from Annual Monocultures to Perennial Polycultures.”
62 Edstedt and Carton, “The Benefits That (Only) Capital Can See? Resource Access and Degradation in Industrial Carbon Forestry, Lessons from the CDM in Uganda”; Milne et al., “Learning from ‘Actually Existing’ REDD+: A Synthesis of Etnographic Findings”; Leach and Scoones, Carbon Conflicts For. Landscapes Africa; Cavanagh and Benjaminsen, “Virtual Nature, Violent Accumulation: The ‘spectacular Failure’ of Carbon Offsetting at a Ugandan National Park”; Corbera and Friedli, “Planting Trees through the Clean Development Mechanism: A Critical Assessment”; Osborne, “Tradeoffs in Carbon Commodification: A Political Ecology of Common Property Forest Governance.”
63 Fairhead, Leach, and Scoones, “Green Grabbing: A New Appropriation of Nature?,” 242.
64 Cusack et al., “An Interdisciplinary Assessment of Climate Engineering Strategies.”
65 Van Vuuren et al., “Alternative Pathways to the 1.5 °c Target Reduce the Need for Negative Emission Technologies.”
66 Tavoni and Socolow, “Modeling Meets Science and Technology: An Introduction to a Special Issue on Negative Emissions,” 7.
67 Battistoni, “There’s No Time for Gradualism.”
Anderson, Kevin. “Duality in Climate Science.” Nature Geoscience 8, no. 12 (2015): 898–900. https://doi.org/10.1038/ngeo2559.
Anderson, Kevin, and Glen Peters. “The Trouble with Negative Emissions.” Science 354, no. 6309 (2016): 182–83. https://doi.org/10.1126/science.aah4567.
Azar, Christian, Kristian Lindgren, Eric Larson, and Kenneth Möllersten. “Carbon Capture and Storage from Fossil Fuels and Biomass - Costs and Potential Role in Stabilizing the Atmosphere.” Climatic Change 74, no. 1–3 (2006): 47–79. https://doi.org/10.1007/s10584-005-3484-7.
Battistoni, Alyssa. “There’s No Time for Gradualism.” Jacobin, October 2018. https://jacobinmag.com/2018/10/climate-change-united-nations-report-nordhaus-nobel.
Beck, Silke, and Martin Mahony. “The IPCC and the Politics of Anticipation.” Nature Climate Change 7, no. 5 (2017): 311–13. https://doi.org/10.1038/nclimate3264.
———. “The Politics of Anticipation: The IPCC and the Negative Emissions Technologies Experience.” Global Sustainability 1 (2018): e8. https://doi.org/10.1017/sus.2018.7.
Carbon Brief. “Q&A: How ‘Integrated Assessment Models’ Are Used to Study Climate Change,” 2018. https://www.carbonbrief.org/qa-how-integrated-assessment-models-are-used-to-study- climate-change.
Carrington, Damian, and Jelmer Mommers. “‘Shell Knew’: Oil Giant’s 1991 Film Warned of Climate Change Danger.” The Guardian, 2017. https://www.theguardian.com/environment/2017/feb/28/shell-knew-oil-giants-1991-film- warned-climate-change-danger.
Carton, Wim. “‘Fixing’ Climate Change by Mortgaging the Future: Negative Emissions, Spatiotemporal Fixes, and the Political Economy of Delay.” Antipode 51, no. 3 (June 22, 2019): 750–69. https://doi.org/10.1111/anti.12532.
Cavanagh, Connor, and Tor A. Benjaminsen. “Virtual Nature, Violent Accumulation: The ‘spectacular Failure’ of Carbon Offsetting at a Ugandan National Park.” Geoforum 56 (2014): 55–65. https://doi.org/10.1016/j.geoforum.2014.06.013.
Corbera, Esteve, and Charlotte Friedli. “Planting Trees through the Clean Development Mechanism: A Critical Assessment.” Ephemera 12, no. 1/2 (2012): 206–41.
Crews, Timothy E., Wim Carton, and Lennart Olsson. “Is the Future of Agriculture Perennial? Imperatives and Opportunities to Reinvent Agriculture by Shifting from Annual Monocultures to Perennial Polycultures.” Global Sustainability 1 (November 13, 2018): e11. https://doi.org/10.1017/sus.2018.11.
Cusack, Daniela F., Jonn Axsen, Rachael Shwom, Lauren Hartzell-Nichols, Sam White, and Katherine R.M. Mackey. “An Interdisciplinary Assessment of Climate Engineering Strategies.” Frontiers in Ecology and the Environment 12, no. 5 (2014): 280–87. https://doi.org/10.1890/130030.
68 Anderson, “Duality in Climate Science.”
Demeritt, David. “The Construction of Global Warming and the Politics of Science.” Annals of the Association of American Geographers 91, no. 2 (2001): 307–37. http://onlinelibrary.wiley.com/doi/10.1111/0004-5608.00245/abstract.
Dooley, Kate, Peter Christoff, and Kimberly A. Nicholas. “Co-Producing Climate Policy and Negative Emissions: Trade-Offs for Sustainable Land-Use.” Global Sustainability 1 (2018): e3. https://doi.org/10.1017/sus.2018.6.
Edstedt, Karin, and Wim Carton. “The Benefits That (Only) Capital Can See? Resource Access and Degradation in Industrial Carbon Forestry, Lessons from the CDM in Uganda.” Geoforum, no. 97 (2018): 315–23. https://doi.org/10.1016/j.geoforum.2018.09.030.
European Academies Science Advisory Council (EASAC). Negative Emission Technologies: What Role in Meeting Paris Agreement Targets? EASAC Policy Report, 2018. https://easac.eu/fileadmin/PDF_s/reports_statements/Negative_Carbon/EASAC_Report_on_N egative_Emission_Technologies.pdf.
Evans, Simon. “In-Depth: Is Shell’s New Climate Scenario as ‘Radical’ as It Says?” Carbon Brief, 2018. https://www.carbonbrief.org/in-depth-is-shells-new-climate-scenario-as-radical-as-it-says.
Fairhead, James, Melissa Leach, and Ian Scoones. “Green Grabbing: A New Appropriation of Nature?” The Journal of Peasant Studies 39, no. 2 (2012): 237–61. https://doi.org/10.1080/03066150.2012.671770.
Fuss, Sabine, Josep G Canadell, Glen P. Peters, Massimo Tavoni, Robbie M. Andrew, Philippe Ciais, Robert B. Jackson, et al. “Betting on Negative Emissions.” Nature Climate Change 4, no. 10 (2014): 850–53. https://doi.org/10.1038/nclimate2392.
Geden, Oliver. “Politically Informed Advice for Climate Action.” Nature Geoscience 11, no. JUNE (2018): 380–83. https://doi.org/10.1038/s41561-018-0142-4.
———. “The Paris Agreement and the Inherent Inconsistency of Climate Policymaking.” Wiley Interdisciplinary Reviews: Climate Change 7, no. 6 (2016): 790–97. https://doi.org/10.1002/wcc.427.
Harper, Anna B., Tom Powell, Peter M. Cox, Joanna House, Chris Huntingford, Timothy M. Lenton, Stephen Sitch, et al. “Land-Use Emissions Play a Critical Role in Land-Based Mitigation for Paris Climate Targets.” Nature Communications 9, no. 1 (2018). https://doi.org/10.1038/s41467-018- 05340-z.
Hickman, Leo. “Timeline: How BECCS Became Climate Change’s ‘Saviour’ Technology.” Carbon Brief, 2016. https://www.carbonbrief.org/beccs-the-story-of-climate-changes-saviour-technology.
Intergovernmental Panel on Climate Change (IPCC). Climate Change 2014: Mitigation of Climate Change. Working Group III Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, 2014. https://doi.org/10.1017/CBO9781107415416.
———. “Global Warming of 1.5°C: An IPCC Special Report on the Impacts of Global Warming of 1.5 °C above Pre-Industrial Levels and Related Global Greenhouse Gas Emission Pathways, in the Context of Strengthening the Global Response to the Threat of Climate Change,” 2018. http://report.ipcc.ch/sr15/pdf/sr15_spm_final.pdf.
Jasanoff, Sheila. “A New Climate for Society.” Theory, Culture and Society 27, no. 2 (2010): 233–53. https://doi.org/10.1177/0263276409361497.
———, ed. States of Knowledge: The Co-Production of Science and the Social Order. New York: Routledge, 2004.
Klein, David, Florian Humpenöder, Nico Bauer, Naomi E Vaughan, Clair Gough, Michael J Walsh, Léda Gerber Van Doren, et al. “Global Economic Consequences of Deploying Bioenergy with Carbon Capture and Storage (BECCS).” Environmental Research Letters 11, no. 095004 (2016): 1–9.
Kriegler, Elmar, Ottmar Edenhofer, Lena Reuster, Gunnar Luderer, and David Klein. “Is Atmospheric Carbon Dioxide Removal a Game Changer for Climate Change Mitigation?” Climatic Change 118, no. 1 (2013): 45–57. https://doi.org/10.1007/s10584-012-0681-4.
Larkin, Alice, Jaise Kuriakose, Maria Sharmina, and Kevin Anderson. “What If Negative Emission Technologies Fail at Scale? Implications of the Paris Agreement for Big Emitting Nations.” Climate Policy 3062, no. August (2017): 1–25. https://doi.org/10.1080/14693062.2017.1346498.
Leach, Melissa, and Ian Scoones. Carbon Conflicts and Forest Landscapes in Africa. Edited by Melissa Leach and Ian Scoones. New York: Routledge, 2015.
Lenzi, Dominic. “The Ethics of Negative Emissions.” Global Sustainability 1 (2018): 1–8. https://doi.org/https://doi.org/10.1017/sus.2018.546.
Low, Sean. “The Futures of Climate Engineering.” Earth’s Future 5 (2017): 67–71. https://doi.org/10.1002/eft2.182.
Mahony, Martin, and Mike Hulme. “Epistemic Geographies of Climate Change.” Progress in Human Geography, 2016, 030913251668148. https://doi.org/10.1177/0309132516681485.
Markusson, Nils, Duncan McLaren, and David Tyfield. “Towards a Cultural Political Economy of Mitigation Deterrence by Negative Emissions Technologies (NETs).” Global Sustainability 1 (2018): 1–9. https://doi.org/10.1017/sus.2018.10.
McGrath, Matt. “Caution Urged over Use of ‘carbon Unicorns’ to Limit Warming.” BBC News, 2018. https://www.bbc.com/news/science-environment-45742191.
Milne, Sarah, Sango Mahanty, Phuc To, Wolfram Dressler, Peter Kanowski, and Maylee Thavat. “Learning from ‘Actually Existing’ REDD+: A Synthesis of Etnographic Findings.” Conservation and Society, 2018, 1–12. https://doi.org/10.4103/cs.cs_18_13.
Minx, Jan C, William F Lamb, Max W Callaghan, Sabine Fuss, Jérôme Hilaire, Dominic Lenzi, Gregory Nemet, et al. “Negative Emissions: Part 1 - Research Landscape, Ethics and Synthesis.” Environmental Research Letters 13 (2018).
Nordhaus, William D. A Question of Balance: Weighing the Options on Global Warming Policies. New Haven and London: Yale University Press, 2008.
———. “An Optimal Transision Path for Controlling Greenhouse Gases.” Science 258, no. 5086 (1992): 1315–19.
———. “Projections and Uncertainties about Climate Change in an Era of Minimal Climate Policies.” American Economic Journal: Economic Policy 10, no. 3 (2018): 333–60. http://cowles.yale.edu/.
Osborne, Tracey. “Tradeoffs in Carbon Commodification: A Political Ecology of Common Property Forest Governance.” Geoforum 67 (2015): 64–77. https://doi.org/10.1016/j.geoforum.2015.10.007.
Parson, Edward A. “Climate Policymakers and Assessments Must Get Serious about Climate Engineering.” Proceedings of the National Academy of Sciences 114, no. 35 (2017): 9227–30. https://doi.org/10.1073/pnas.1713456114.
Peters, Glen P., and Oliver Geden. “Catalysing a Political Shift from Low to Negative Carbon.” Nature 15
Climate Change, 2017. https://doi.org/10.1038/nclimate3369.
Pindyck, Robert S. “The Use and Misuse of Models for Climate Policy.” Review of Environmental
Economics and Policy 11, no. 1 (2017): 100–114. https://doi.org/10.1093/reep/rew012.
Riahi, Keywan, Detlef P. van Vuuren, Elmar Kriegler, Jae Edmonds, Brian C. O’Neill, Shinichiro Fujimori, Nico Bauer, et al. “The Shared Socioeconomic Pathways and Their Energy, Land Use, and Greenhouse Gas Emissions Implications: An Overview.” Global Environmental Change 42 (2017): 153–68. https://doi.org/10.1016/j.gloenvcha.2016.05.009.
Schleussner, Carl-friedrich, Joeri Rogelj, Michiel Schaeffer, Tabea Lissner, Rachel Licker, Erich M Fischer, Reto Knutti, Anders Levermann, Katja Frieler, and William Hare. “Science and Policy Characteristics of the Paris Agreement Temperature Goal.” Nature Climate Change 6, no. July (2016): 827–35. https://doi.org/10.1038/NCLIMATE3096.
Scott, Vivian, and Oliver Geden. “The Challenge of Carbon Dioxide Removal for EU Policy-Making.” Nature Energy, 2018, 2016–18. https://doi.org/10.1038/s41560-018-0124-1.
Shell. “Energy Transition Report,” 2018. https://www.shell.com/energy-and-innovation/the-energy- future/shell-energy-transition- report/_jcr_content/par/toptasks.stream/1524757699226/f51e17dbe7de5b0eddac2ce19275dc 946db0e407ae60451e74acc7c4c0acdbf1/web-shell-energy-transition-report.pdf.
———. “Shell Scenarios: Sky - Meeting the Goals of the Paris Agreement,” 2018. https://www.shell.com/promos/meeting-the-goals-of-the-paris- agreement/_jcr_content.stream/1521983847468/5f624b9260ef2625f319558cbb652f8b23d331 933439435d7a0fc7003f346f94/shell-scenarios-sky.pdf.
———. “Sky Scenario,” 2018. https://www.shell.com/energy-and-innovation/the-energy- future/scenarios/shell-scenario-sky.html.
Shue, Henry. “Climate Dreaming: Negative Emissions, Risk Transfer, and Irreversibility.” Journal of Human Rights and the Environment 8, no. 2 (2017): 203–16. https://doi.org/10.1038/nature18307.
Smith, Pete, Steven J Davis, Felix Creutzig, Sabine Fuss, and Jan Minx. “Biophysical and Economic Limits to Negative CO2 Emissions.” Nature Climate Change 6, no. December (2016): 42–50. https://doi.org/10.1038/NCLIMATE2870.
Stanton, Elizabeth A., Frank Ackerman, and Sivan Kartha. “Inside the Integrated Assessment Models: Four Issues in Climate Economics.” Climate and Development 1, no. 2 (2009): 166–84. https://doi.org/10.3763/cdev.2009.0015.
Stern, Nicholas. “The Structure of Economic Modeling of the Potential Impacts of Climate Change: Grafting Gross Underestimation of Risk onto Already Narrow Science Models.” Journal of Economic Literature 51, no. 3 (2013): 838–59. https://doi.org/10.1257/jel.51.3.838.
Tavoni, Massimo, and Robert Socolow. “Modeling Meets Science and Technology: An Introduction to a Special Issue on Negative Emissions.” Climatic Change 118, no. 1 (2013): 1–14. https://doi.org/10.1007/s10584-013-0757-9.
Turnhout, Esther. “The Politics of Environmental Knowledge.” Conservation and Society 16, no. 3 (2018): 363–71.
Turnhout, Esther, Katja Neves, and Elisa De Lijster. “‘Measurementality’ in Biodiversity Governance: Knowledge, Transparency, and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (Ipbes).” Environment and Planning A 46, no. 3 (2014): 581–97.
Vaughan, Adam. “Shell Boss Says Mass Reforestation Needed to Limit Temperature Rises to 1.5C.” The Guardian, 2018. https://www.theguardian.com/business/2018/oct/09/shell-ben-van- beurden-mass-reforestation-un-climate-change-target.
Vuuren, Detlef P. Van, Michel G.J. Den Elzen, Paul L. Lucas, Bas Eickhout, Bart J. Strengers, Bas Van Ruijven, Steven Wonink, and Roy Van Houdt. “Stabilizing Greenhouse Gas Concentrations at Low Levels: An Assessment of Reduction Strategies and Costs.” Climatic Change 81, no. 2 (2007): 119–59. https://doi.org/10.1007/s10584-006-9172-9.
Vuuren, Detlef P. Van, Elke Stehfest, David E.H.J. Gernaat, Maarten Van Den Berg, David L. Bijl, Harmen Sytze De Boer, Vassilis Daioglou, et al. “Alternative Pathways to the 1.5 °c Target Reduce the Need for Negative Emission Technologies.” Nature Climate Change 8, no. 5 (2018): 391–97. https://doi.org/10.1038/s41558-018-0119-8.
Vuuren, Detlef P Van, Andries F Hof, Mariësse A E Van Sluisveld, and Keywan Riahi. “Open Discussion of Negative Emissions Is Urgently Needed.” Nature Energy, 2017. https://doi.org/10.1038/s41560-017-0055-2.